Prevention of accidental exposure in radiotherapy
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IAEA Training C ourse. PREVENTION OF ACCIDENTAL EXPOSURE IN RADIOTHERAPY. Part 6 : Case histories of major accidents with abandoned radiotherapy sources. Overview / Objectives. Module 6.1 : Source not under control (Brazil) Module 6.2 : Source not under control (Mexico)

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IAEA TrainingCourse

PREVENTION OF ACCIDENTAL EXPOSURE IN RADIOTHERAPY

Part 6: Case histories of major accidents with abandoned radiotherapy sources


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Overview / Objectives

  • Module 6.1: Source not under control (Brazil)

  • Module 6.2: Source not under control (Mexico)

  • Module 6.3: Source not under control (Turkey and Thailand)

  • Group exercise G7 : Public exposure

Objectives: To review and analyze case histories of major accidents involving abandoned radiotherapy sources

Prevention of accidental exposure in radiotherapy


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IAEA Training Course

Module 6.1: Source not under control (Brazil)


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Background information

Prevention of accidental exposure in radiotherapy


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Background information

  • Year 1985, a private radio-therapy institute, Instituto Goiano de Radioterapia (IGR), had two external beam treatment units:

    • Cobalt-60 teletherapy unit

    • Caesium-137 teletherapy unit

Prevention of accidental exposure in radiotherapy


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Background information

  • The institute was situated in Goiânia, population ~1M, in central Brazil.

  • Both the 60Co and 137Cs units had gone through proper licensing procedures with CNEN (Regulatory Authority)

Rio de Janeiro

Prevention of accidental exposure in radiotherapy


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Background information

  • CNEN is the Regulatory Authority, operating a licensing system relating to individuals (certifying training) and facilities (licensing operation of facilities).

  • Federal Ministry of Health had responsibilities for subsequent inspections of medical facilities. This was also devolved to State Health Secretaries.

Prevention of accidental exposure in radiotherapy


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Description of the Cs-unit

  • The radiation head is adjustable vertically and can be rotated about two horizontal axes

  • Inside the radiation head is a rotating assembly with the sealed 137Cs source

Prevention of accidental exposure in radiotherapy


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Description of the Cs-unit

  • A source wheel forms a rotating shutter mechanism with the source

  • To produce a beam, the shutter is rotated electrically to align the source with an aperture

Prevention of accidental exposure in radiotherapy


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Description of the Cs-unit

  • Cross-section of international standard capsule

  • Source material was inside two stainless steel capsules, inside a standard capsule

Prevention of accidental exposure in radiotherapy


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Description of the Cs-unit

  • Source material: 137Cs chloride salt (which is highly soluble) – 93 g

  • Sep. 1987: 50.9 TBq; 4.56 Gy/h at 1 m

Prevention of accidental exposure in radiotherapy


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Description of the event

Prevention of accidental exposure in radiotherapy


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At the end of 1985, the IGR ceased operations at the old site and a new partnership took over the old site

The 60Co unit was moved to the new site

Start of the event

Prevention of accidental exposure in radiotherapy


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Start of the event site and a new partnership took over the old site

  • Ownership of the contents of the old site became disputed

  • The 137Cs unit was left behind at the old site

  • CNEN did not receive appropriate notification of these changes in status

Prevention of accidental exposure in radiotherapy


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Start of the event site and a new partnership took over the old site

  • Most of the old site was demolished.

  • The treatment rooms were not demolished but were left in a derelict state and apparently used by vagrants.

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

NB! Original drawing made at time of discovery differs in details from description of event

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

10-13 Sep. 1987

  • RA and WP went to old site of IGR on rumours that valuable equipment had been left behind, and tried to dismantle Cs-unit with simple tools.

  • They succeeded in removing rotating assembly in its stainless steel casing.

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

10-13 Sep. 1987

  • RA and WP took the rotating assembly in a wheelbarrow to RA’s house.

  • {no contamination was found at clinic – source assembly probably still intact}

  • {they would potentially have been exposed to the direct beam}

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

13-15 Sep. 1987

  • WP and RA were vomiting, assuming this was due to something eaten

  • WP had diarrhoea, one hand swollen, sought medical assistance

  • Symptoms diagnosed as allergic reaction due to bad food

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

13-18 Sep. 1987

  • Rotating assembly had been placed in RA’s yard, near houses rented out by RA’s mother

  • RA worked to remove the source wheel intermittently

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

18 Sep. 1987

  • RA succeeded in removing the source wheel eventually

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

18 Sep. 1987

  • In the course of removing the source wheel, the 1 mm window of the source capsule was punctured with a screwdriver and some of the source was scooped out

  • {residual contamination (2 Oct) under the mango tree gave a dose rate of 1.1 Gy/h at 1m}

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

18 Sep. 1987

  • Rotating assembly pieces were sold to junkyard manager DF. Pieces were transported by employee of DF to garage in junkyard

  • That night, DF noticed a blue glow from the source capsule. He thought the powder might be valuable

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

18-21 Sep. 1987

  • DF took the capsule into the house. Over the next three days, various neighbours, relatives and acquaintances were invited to see the capsule as a curiosity

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

18-21 Sep. 1987

  • DF and his wife MF1 examined the powder closely

  • {MF1 (D=5.7 Gy) subsequently died. DF (D=7.0 Gy) survived, possibly due to fractionation arising from him being in and out of the house}

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

21 Sep. 1987

  • EF1 visited DF and removed fragments of source from capsule. EF1 gave some fragments to his brother EF2 and took the rest home.

  • DF also distributed fragments to his family. Some persons applied powder on skin as glitter.

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

21-23 Sep. 1987

  • MF1 was vomiting and had diarrhoea. After examination in hospital, MF1 was sent home and her mother MA1 came over for two days to nurse her

  • MA1 returned home on the bus, taking contamination with her

  • {MA1 (D=4.3 Gy) survived}

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

22-24 Sep. 1987

  • DF’s employees, IS and AS worked on the rotating assembly with the unshielded source to extract lead. ZS visited, offered to cut up pieces with torch, but forgot to do so

  • {IS (D=4.5 Gy) and AS (D=5.3 Gy) subsequently died}

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

24 Sep. 1987

  • IF, the brother of DF, was given source fragments, took them home, and placed them on the table during the meal

  • His six year old daughter, LF2, handled them while eating

  • {LF2 (D=6.0 Gy) subsequently died}

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

24-28 Sep. 1987

  • The parts spread to two more junkyards

  • By 28 Sep. a significant number of people were physically ill

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

28 Sep. 1987

  • MF1 was convinced that the glowing powder was causing the sickness

  • Source assembly was taken to small clinic in bag, left to Dr. PM, who got worried enough to put bag in yard

  • Dr. AM at Toxicological Information Centre was contacted

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

28 Sep. 1987

  • Dr. JP at the State Department of the Environment was in turn contacted. He proposed that a Medical Physicist should have a look at the suspicious package

  • The pace of the events then quickened as the seriousness of the accident began to be appreciated

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

29 Sep. 1987

08:00-11:00

  • Medical Physicist WF was contacted and became convinced (from scintillation detector readings) that a major radiation source was at the clinic

  • The clinic was vacated. Police and fire brigade stopped building being entered

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

29 Sep. 1987

12:00-15:00

  • Radiation monitor showed contamination at first junkyard which was vacated

  • State Secretary for Health was informed of incident and its significance and to obtain further assistance

  • Director of the Department of Nuclear Installations in CNEN (coordinator for nuclear emergencies) was contacted

  • IGR was contacted, who tentatively identified source as possibly originating from IGR

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

29 Sep. 1987

16:00-20:00

  • Hospitals were informed of potential radiation exposure to a number of people

  • Civil defence forces were alerted

  • Known sites of contamination were resurveyed

  • State Health Secretary made plans for receiving contaminated persons in city’s stadium

  • Press was taking an interest

  • More sites of major contamination were identified

Prevention of accidental exposure in radiotherapy


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Chronology of the event site and a new partnership took over the old site

  • The physicist WF monitoring for contamination at the stadium

Prevention of accidental exposure in radiotherapy


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Extent of the accident site and a new partnership took over the old site

Prevention of accidental exposure in radiotherapy


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Extent of the accident site and a new partnership took over the old site

  • 112,000 persons were monitored

  • 249 of these had external / internal contamination (up to 7 Gy)

  • 129 of these had both external and internal contamination

  • 49 of these were admitted to hospital

  • 20 of these needed intensive medical care

  • 10 of these were in critical conditions

  • 4 of these died (within four weeks) and one had to have the forearm amputated

Prevention of accidental exposure in radiotherapy


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Extent of the accident site and a new partnership took over the old site

Prevention of accidental exposure in radiotherapy


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Extent of the accident site and a new partnership took over the old site

  • 7 main foci of contamination within 1 km2

  • Dose rates up to 2 Sv/h at 1 m from contamination

  • 41 houses were evacuated

  • Contamination was removed from 45 different public places, and it was also found on 50 vehicles

  • Extensive rains dispersed the highly soluble caesium chloride into the environment

Prevention of accidental exposure in radiotherapy


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Actions taken site and a new partnership took over the old site

Prevention of accidental exposure in radiotherapy


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Actions taken site and a new partnership took over the old site

  • Remember the cardinal rule of radiation protection: The security of the source is of paramount importance!

  • This was an Emergency Exposure Situation (BSS). The Regulatory Authority CNEN was contacted

  • Civil defence (police, etc.) was contacted

  • Intervention was enacted based on action levels (e.g. evacuation, decontamination, removal of soil)

Prevention of accidental exposure in radiotherapy


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Actions taken site and a new partnership took over the old site

  • For accidents like this, the actions to be taken can be divided into two phases:

  • The initial phase, when urgent action is required

    • To identify potential sources of acute exposure

    • To bring exposure under control

  • The recovery phase, when urgent action is no longer required and the objective is to restore the situation to normal

Prevention of accidental exposure in radiotherapy


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Actions taken site and a new partnership took over the old site

  • Initial phase

  • Identification of main contamination sites

  • Evacuation at sites above intervention levels

  • Control areas through access prevention

  • Identification of persons who had incurred significant doses or were contaminated

    + Medical response, of course!

Prevention of accidental exposure in radiotherapy


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Actions taken site and a new partnership took over the old site

  • Medical response

  • Specialists dispatched to Goiânia

  • Severe external and internal contamination with Cs-137

  • External decontamination was performed

  • “Prussian Blue” was used for internal decontamination

  • Acute radiation syndrome and local injuries were treated

Prevention of accidental exposure in radiotherapy


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Actions taken site and a new partnership took over the old site

  • Remedial actions

  • Decontamination of property

  • Collection of contaminated clothing

  • Removal of contaminated soil

  • Placing of restrictions on home grown produce

Prevention of accidental exposure in radiotherapy


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Actions taken site and a new partnership took over the old site

  • Seven houses had to be demolished

    Preparing to demolish the house of EF2 near first junkyard

Prevention of accidental exposure in radiotherapy


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Actions taken site and a new partnership took over the old site

  • Removal of waste material

  • The final total volume of waste stored was 3500 m3

  • This represents more than 275 lorry loads

  • Since action levels were chosen restrictively, in relation to international guidelines, this volume became very large and the operation very costly

Prevention of accidental exposure in radiotherapy


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Lessons and recommendations site and a new partnership took over the old site

Prevention of accidental exposure in radiotherapy


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Initiating event and contributory factors site and a new partnership took over the old site

  • The event was triggered by

    • Allowing a source to become in a state of not being secure and under control

  • Contributory factors

    • The solubility and ease of dispersion of the caesium chloride

Prevention of accidental exposure in radiotherapy


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Lessons for prevention site and a new partnership took over the old site

  • The person designated as being liable for a radioactive source must always ensure the source is secure and under control

  • Notify Regulatory Authorities of changes in circumstances relating to sources

  • Physical and chemical properties of sources should be taken into account in licensing

Prevention of accidental exposure in radiotherapy


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Lessons for responses site and a new partnership took over the old site

  • Too restrictive criteria for action levels (in relation to international guidelines) can impose a tremendous burden on public and response team

  • Recognition of the nature of radiation injury depends on education of health and safety professions. This can aid speed of diagnosis and overall speed of response

  • Prompt handling of internal contamination is important. Prussian Blue was shown to aid under these circumstances

Prevention of accidental exposure in radiotherapy


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Goiâna accident summary site and a new partnership took over the old site

  • Caesium-137 source not under control

  • Many people lost their homes

  • 4 persons dead

    Most fatal radiological accidents have occurred outside the nuclear industry

Prevention of accidental exposure in radiotherapy


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Reference site and a new partnership took over the old site

  • IAEA: The Radiological Accident in Goiânia (1988)

rpop.iaea.org

Prevention of accidental exposure in radiotherapy


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